As engines and applications have evolved, there has been a need for reducing the size of engines while at the same time increasing the power output available from those engines. When the engine size is reduced, the size of the engine crankshaft is reduced as well. As a result there is less space available for bearings and for stress reducing features such as fillets. To accommodate a shorter crankshaft, undercut fillets that entirely encircle the rod journal have been used. While this may produce the desired reduction in stress on the crankshaft, it may also decrease the stiffness of the crankshaft from that which is desired in the application.
German Patent No. 11916492A1 (“Duetz”) discloses an example of a crankshaft. FIG. 2 discloses a cross-section of a portion of a crankshaft. The crankshaft includes a shaft journal (2), a web (4) and a crank pin (3). To relieve stress, the web (4) has at least one groove cut into it. In one embodiment, the groove is cut on either side of the web (4) cheek at a spaced apart distance from the transition region or fillet region 5, 6 of the crankshaft. The groove, as shown in FIG. 3, may be arc shaped. This design does not disclose an undercut disposed at an offset angle.